Method for the removal of magnetic sound track from movie film



July 30, 1963 R. s. WALSH 3,099,584

METHOD FOR THE REMOVAL OF MAGNETIC SOUND TRACK FROM MOVIE FILM Filed Aug: 8, 1960 2 Sheets-Sheet 1 DRIVE w VEN X SFROCKET at: 1 Fl 6 FEED-ION TAKE-UP 000 7 OOO '7 AIR-KNIFE 2 8 DRIVE GLASS TUBE 4 ULTRRSON 3 TA N K 9 RECIRCULHTION LIN E 5 10 I LTER PUMP W TE 14 A R SOLVENT R oberiSZWalsh/ IN VEN TOR.

R. s. WALSH 3,099,584

METHOD FOR THE REMOVAL OF MAGNETIC SOUND TRACK FROM MOVIE FILM July 30, 1963 2 Sheets-Sheet 2 Filed Aug. 8, 1960 h w a m w m .m 0 V 0 Wm M 6 T e w 4/ w E 2 R K953 ma i 1 25. 8209 53 X m h m om T J W wzfitmm JAI N 0 MW Q- & o moh tmzmw Q EHE w E 252KB: m Z I 5 \W I J zotfibu umm W v a uni mmfiw a 5423 zQRSBQGmm a mum WEEK DEE as QESQ N MRH United States Patent 3,099,584 METHOD FOR THE REMGVAL 0F MAGNETIC SQUND TRACK FROM MOVIE FILM Robert S. Walsh, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Aug. 8, 1960, Ser. No. 48,043 6 Cla ms. (Cl. 134-1) This invention concerns the removal of polymeric coatings from movie film and more particularly a method for removing magnetic ferric oxide particles coated on motion-picture film base with a polymeric binder to provide a magnetic sound track.

In order to provide magnetic sound to motion-picture film, a magnetic sound stripe is added following the processing step. However, care must be taken due to the critical requirements for the sound stripe to have it uniform in width and thickness. For instance, sprocket holes along the side of the film make coating difiicult and may result in sprocket modulation. Therefore, it has sometimes been desirable to remove the magnetic sound stripe from movie film due to variations in width or thickness or imperfections in the sound stripe which renders it unsuitable for use. Since no suitable method has been available, it has been necessary to make a photographic duplicate and add a new sound stripe with the additional expense.

Various methods of treating motion-picture films have been known for protecting the surface such as applying a lacquer on the film surface in order to protect the film from finger-printing, spotting, abrasions and the like. Usually these lacquers have been formulated so that they could be removed by merely passing through processing solutions without requiring any further contact with the film such as a brush or similar wiping mechanism. However, certain lacquers could be used which are not easily removed in alkaline solutions if a suitable solvent system were available for removing these lacquers.

The removal of sound track from motion-picture film requires the use of a solvent sutficiently active to dissolve the binder which has been used to attach the magnetic particles to the film surface but merely passing the film through such a solvent fails to obtain its release. The use of la wiper or brush mechanism rotating against the sound track has been found to be efiective in removing the magnetic oxide but smears the oxide badly so that it is not a satisfactory method.

I have discovered a method of removing the magnetic sound stripe from motion-picture film which does not adversely affect the dyes in color film, which does not smear the magnetic oxide over the photographic image but which removes the track completely and efficiently. This method can also be used to remove film lacquers and dirt from motion-picture film.

One object of this invention is to provide a method for the removal bf a magnetic sound track from motionpieture film effectively without harming the photographic image and without smearing the magnetic oxide on the film. An additional example is to provide a method of using ultrasonic agitation for the removal of a magnetic sound track, lacquer and the like from movie film. A further object is to provide a method of removing undesirable foreign objects from the surface of movie film by the use of ultrasonic agitation.

The above objects are attained by using an apparatus having a solvent container through which the film can be passed which is agitated by means of an ultrasonic vibrator which causes removal of the magnetic sound stripe from the motion-picture film. In my preferred embodiment the solvent container is in a U-shape to 3,099,584 Patented July 30, 1963 "ice facilitate passage of the film through the solvent and this U-shaped container is partly immersed in a water tank which is vibrated in turn by the ultrasonic vibrator. The solvent is recirculated through a filter to remove the iron oxide and other foreign substances from the solvent so that it can more eife-ctively be used to remove additional magnetic sound stripe, etc., from the film and also to avoid clogging the solvent container with magnetic oxide or other debris.

Solvents which may be used for treating a magnetic sound stripe using a cellulose nitrate binder are highly critical. I have found that 4 methyl-2-pentanone (hereafter called methylisobutyl ketone or MIBK), butyl acetate and Z-ethoxyethanol (hereafter called Cellosolve) are preferred. Other solvents which may be used include ethyl propionate, Z-n-butoxyethanol and methanol. Up to 60% toluene may be added to improve the characteristics of cellulose acetate bases. These solvents do not affect adversely cellulose acetate, cellulose triacetate or polyester film base during the time of immersion. They also do not affect the dyes used in color films which are available commercially, nor do they affect the photographic images which are carried on film bases.

The diagrams show embodiments of the apparatus for removal of the magnetic sound stripe of motion-picture film, but mechanical equivalents of this apparatus are intended to be within the scope of my invention.

FIGURE 1 shows a single tube apparatus particularly useful in cleaning or small scale magnetic stripe removal.

The film is passed through a glass tube 8 which holds the solvent '14. The ultrasonic tank 4 surrounding the tube 8 is filled with water 13. Vibrations pass through the water 13, through the glass of tube 8 and then through the solvent 14 to the film 12. The solvent 14 is recirculated through a filter 10 to remove the suspended magnetic oxide. As the film 12 comes out of the glass tube 8, it passes through an air squeegee 7 which blows most of the liquid 14 from the film 12. Some of the solvent 14 is evaporated by the air so that the air knife 7 is enclosed in a box 15 which is vented. The film 12 is driven into the tube 8 and pulled from it by two sprocket wheels 2 and 5. This assures that the film is not under tension in the tube but provides a satisfactory loop. Since the tube is cylindrical in cross-section, only the edges of the film 12 touch the wall and there is no tendency to scratch the film.

The film is attached on the feed-on spool where it passes to the drive sprocket 3 through the glass tube 8 past the air knife 7 to the drive sprocket 5 and to the take-up spool 6. An ultrasonic generator 3 provides the vibrations to the ultrasonic tank 4 through which the vibrations pass to the water 3 and thence through the glass walls to the solvent 14. The solvent 14 contained in the glass tube 8 is recirculated through the recirculation lines 9 by the pump 11 through the filter 10 which removes foreign and undesirable matter from the solvent.

FIGURE 2 shows a two tube embodiment using a first tube for removing most of the magnetic stripe and employing a solvent filtering system. A second tube em ploying a second solvent filtering system removes the balance of the stripe and cleans the film.

The film is passed from the feed-on spool 1 through a glass tube 8 which holds the solvent 14. The ultrasonic tank 4 surrounding the tube 8 is filled with water 13. Ultrasonic vibrations pass through the water 13 through the glass of the tubes 8 and then to the solvent 14 to the film 12. The solvent 14 and the first tube 8 is recircled to the recirculation line 9 through the pump 11 to the settling box 15. A magnet 16 located at the front of the settling box aids in causing the suspended magnetic oxide in the solvent 14 to be deposited in the settling box.

3 The solvent 14 is then passed through the filter 10 to further remove suspended magnetic oxide and recirculated back to glass tube 8. As the film 12 comes out of the first glass tube 8, it passes through a squeegee 18 around a drive wheel 20, an idler wheel 19, and a drive wheel 21 into a second glass tube 8 which is filled with a solvent 14. The solvent 14 in the second tube may be the same as or diifeent from the solvent in the first tube 8, but the second tube 8 has a separate recirculation and filtration system adapted to circulate the solvent 14 through pump 22 and filter 23 to remove any matter which is removed in the second tube 8. After passing through the second tube 8', the film 12 passes through a squeegee 17 and an air knife 7 around a drive wheel to a take-up reel 6.

FIGURE 3 shows a diagram of the preferred embodirrnent of the settling box 15 showing bafiles which aid in depositing magnetic oxide in the bottom of the box 15.

Although glass tubes are shown in our preferred embodiment, other materials may be used to contain the solvent such as stainless steel, polyethylene, polytetrafiuoroethylene, or the like.

Various means may be used to provide the ultrasonic waves which are emitted by a transducer. For instance, it may be desirable to use two transducers or more. It may be desirable to have the transducers shaped in such a way that the waves can be focused on the glass tubes in order to concentrate the effect of the ultrasonic vibrations, or at a point beyond so that divergent waves play on the tube 8'. The ultrasonic waves may be in the range of about to 1000 kilocycles. Suitable transducers may be elongate and arouate in cross-section, being formed of a section of a cylinder. Such curvilinear transducers may be made of barium titanate or any other electrostrictive polycrystalline aggregate, in order to deliver intense sonic energy to the focus of the transducer.- From the focus the waves disperse themselves radially over a very wide area.

' .The following examples are intended to illustrate my invention but are not intended to limit it in any way:

Example I The following color films were passed through the apparatus using methylisobutyl ketone as the solvent and water in the-ultrasonic tank:

Reversal type color film (dyes added during processing) Reversal type color film (with incorporated coupler) Negative type color film (with incorporated coupler) Positive type color film (with incorporated coupler) The films were in the methyliso-butyl ketone about 34 seconds. This is two to three times the time necessary under agitation to remove the magnetic stripe, but a longer time was used in order to exaggerate dye losses. No dye loss or dye change was apparent with the solvents in any of the color films tested. These color films were typical of color films commercially available and of the various type color processes.

Example 11 Dye stability tests were run using butyl acetate on the color motion-picture films tested in Example I under the same circumstances with the film remaining in the solvent about 34 seconds. Satisfactory results were obtained as in Example 1.

Example III Dye stability tests were run with Cellosolve as were run in Example I but the film was in the solvent for about 60 seconds. No loss or dye change was apparent with this solvent.

The samples from Examples I-III of reversal color film of the type in which the dyes are added during processing were tested with various physical tests for brittleness, scratch, curl and tensile strength against a check sample which had not been run through the solvents. There was no significant difierence between the tests of the check "i film and the film treated with methylisobutyl ketone or butyl acetate in the brittleness, curl, tensile strength or scratch resistance. Film treated with Cellosolve had about the same brittleness as the check film but had more negative curl and somewhat less tensile strength. A test of the film base showed that no significant amount of plasticizer had been extracted.

I have found that this method may be used to remove various types of lacquer applied over motion-picture rfilrns, particularly with respect to lacquers which require a solvent for removal. Such a lacquer might be based on cellulose nitrate or might be made of a polymeric material such as polyvinylbutyral, an acrylic copolymer or the like. Also, this apparatus might be used for film cleaning using a mild solvent such as methyl chloroform which will not harm the film base or the dyes used in color films.

Various film bases may be employed such as cellulose acetate, cellulose triacetate, mixed esters of cellulose such as cellulose acetate butyrate, vinyl polymers, polyolefins such as polyethylene, polypropylene, polyethylene terephthalate, other polyester bases or the like.

In my preferred embodiment two steps are employed involving a first solvent treatment using a solvent which may be butyl acetate, Cellosolve or methylisobutyl ketone. In the second step the film is passed through a mild inert solvent such as methyl chloroform which further removes any debris which may not have been completely removed in the first step.

The method of the above invention may also be used to remove dirt and the like from other photographic elements such as photographic transparencies. The apparatus disclosed above may also be used for rapidly processing motion-picture film by incorporating developer solutions in the first tube and 1a fixing solution in the second tube. Other tubes may of course be added to the apparatus disclosed embodying the principle of using ultrasonic vibrations to provide agitation for the processing steps.

Prior to applying a magnetic stripe on processed photographic film it is frequently necessary to clean the film to remove dirt, fingerprints, and the like, since applying the magnetic stripe over such foreign materials may result in distortions. In addition, motion-picture film is prone to the build up of static charges. Localized static charges in the film that is being coated with a magnetic stripe cause pips to form in the stripe which will affect amplitude modulation and frequency response to a degree that depends on their frequency and intensity.

In my preferred embodiment a film is cleaned using the apparatus disclosed herein using methyl chloroform or similar material. Typical film cleaners which may be used are methyl alcohol, ethyl alcohol, trichloboethylene, methyl chlonoforrn, and the like. These may also be applied using a device consisting of two cloth pads held in :a metal clamp attached to a grounded frame. One pad touches the emulsion side :of the film and the other touches the film support. These pads are kept wet with solvent during the cleaning operation.

In the event that film lubrication is desired, a concentration of 0.5 to 1.5 gram of wax per liter of solvent may be used. Satisfactory waxes are the pen-taerythritol stearrates, opal wax, camaub-a wax, candellila, and other natural and synthetic soluble waxes. The addition of these Waxes to the film cleaner aids in film preservation.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the mvention as described hereinabove and as defined in the appended claims.

I claim:

1. A method for removing the magnetic stripe from motionpicture film comprising immersing the motionpicture film in a solvent selected from the class consisting of methylisobutyl ketone, butyl acetate and Z-ethoxyethanol while the solvent is being agitated by means of ultrasonic vibrations.

2. A method for removing a magnetic sound stripe essentially consisting of a magnetic oxide in a cellulose nitrate binder firom motion-picture film comprising continuously passing the motion-picture film through an organic solvent selected fmom the class consisting of methylisobn-tyl ketone, butyl acetate and ZethoXyethanol during which time the solvent is continuously agitated by means of ultrasonic vibrations.

3. A method for removing a magnetic sound stripe from motiompicture film comprising a tw0=stepprocess, the first step in which the motion-picture film is passed through an organic solvent selected from the class consisting :of methylisobutyl ketone, butyl acetate and 2- ethoxyethanol during which time the solvent is agitated by means of ultrasonic v'brations, afiter which the solvent is removed from the magnetic film and the film is passed into a second container containing an inert solvent to the motion-picture film base, the photognaphic image and the dyes used therein during which time the solvent is agitated by means of ultrasonic vibrations.

4. Claim 1 wherein the solvent is butyl acetate.

5. A method for removing magnetic stripe having a polymeric binder fnom motion-picture film which comprises immersing the film in 'an organic liquid agitated with ultrasonic vibrations, which liquid is a solvent tot the magnetic stripe and is substantially inert with respect to the film base and the photographic material carried thereon.

6'. A method for removing magnetic stripe having a polymeric binder from motion-picture film which comprises immersing the film in an organic liquid agitated with ultrasonic vibrations, which liquid is a solvent for the magnetic stripe and, at least during the time required to remove the magnetic sttipe, is substantially inert with respect to the film base and the photographic material carried thereon.

References Cited in the file of this patent UNITED STATES PATENTS 2,650,603 Howes Sept. 1, 1953 2,676,599 McHenry Apr. 27, 1954 2,702,260 Massa Feb. 15, 1955 2,802,758 Kearney Aug. 13, 1957 2,894,860 En-gclhardt July 14, 1959 2,937,111 Leithanser May 17, 1960 2,967,119 Gutterman Jan. 3, 19611 

5. A METHOD FOR REMOVING MAGNETIC STRIPE HAVING A POLYMERIC BINDER FROM MOTION-PICUTRE FILM WHICH COMPRISES IMMERSING THE FILM IN AN ORGANIC LIQUID AGITATED WITH ULTRASONIC VIBRATIONS, WHICH LIUID IS A SOLVENT FOR THE MAGNETIC STRIPE AND IS SUBSTANTIALLY INERT WITH RESPECT 